100 lines
2.7 KiB
Python
100 lines
2.7 KiB
Python
# Copyright (C) 2015 Ericsson AB
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# Copyright (c) 2015 Gigamon
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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#
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# This class implements a simple key-value manager that can support
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# the following relationships.
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#
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# - Multiple values may be affiliated with a key.
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# - A value may be affiliated with multiple keys.
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# - A value may be affiliated with a key multiple times.
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#
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class key_value_mgr(object):
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#
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# Initializes internal state for specified # keys
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#
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def __init__(self, nr_keys):
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self.key_list = []
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for i in range(nr_keys):
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self.key_list.append([])
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return
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#
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# Returns specified key-value affilation, if it exists.
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#
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def _find_affiliation(self, key, value):
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aff_list = self.key_list[key]
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for aff in aff_list:
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if aff['value'] == value:
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return aff
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return None
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#
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# Adds an affiliation of 'value' with 'key'
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#
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def affiliate(self, key, value):
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# Locate key-value affiliation
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aff = self._find_affiliation(key, value)
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if aff is None:
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# Create a (new) key-value affiliation
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aff = {
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'value': value,
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'refcnt': 0,
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}
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aff_list = self.key_list[key]
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aff_list.append(aff)
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# Increment affiliation reference count
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aff['refcnt'] += 1
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return
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#
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# Removes an affiliation of 'value' with 'key'
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#
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def unaffiliate(self, key, value):
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# Locate key-value affiliation
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aff = self._find_affiliation(key, value)
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if aff is None:
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return
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# Decrement affiliation reference count
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aff['refcnt'] -= 1
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# Destroy affiliation iff no outstanding references
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if aff['refcnt'] <= 0:
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aff_list = self.key_list[key]
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aff_list.remove(aff)
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return
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#
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# Lists all values affiliated with 'key'
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#
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# Note: The returned list is a set (contains no duplicates)
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#
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def list_affiliations(self, key):
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aff_list = self.key_list[key]
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value_list = []
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for aff in aff_list:
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value_list.append(aff['value'])
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return value_list
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